A droplet actuator typically includes one or more substrates configured to form a surface or gap for conducting droplet operations. The one or more substrates establish a droplet operations surface or gap for conducting droplet operations and may also include electrodes arranged to conduct the droplet operations. The droplet operations substrate or the gap between the substrates may be coated or filled with a filler fluid that is immiscible with the liquid that forms the droplets.
Droplet actuators are used in a variety of applications, including molecular diagnostic testing, such as point-of-care testing in which the flexibility and breadth of digital microfluidics provide a rapid and sensitive multifunctional testing device. For point-of-care testing, diagnostic devices are typically provided pre-loaded with the required assay reagents for a diagnostic test. Consequently, there is a need for methods for storing assay reagents on a droplet actuator.